High-reliability hybrid integrated DC/DC converter (HHW28 series)
1. Features (see Fig. 1 for outside view, and Table 1 for models)
Range of input DC voltage: 18~36V, nominal input DC voltage 28V
Output power: 20W
Operating temperature (Tc): -55~+105℃
Input, output and case are isolated mutually
Insulation resistance: R≥100MΩ (DC 500V)
With the function of inhibit and short-circuit protection
Power density: 28W/in3
Totally sealed metal case

2. Scope of application 
High-reliability electronic system for aviation and aerospace, etc.

3. Description
HHW28 series high-reliability DC/DC converter can work at 28V input voltage, and the output power is 20W.The case of this series is of totally sealed metal structure with fixed end or without fixed end.
HTW28 series products adopt PWM push-pull technology, and the constant switching frequency is 200~300kHz. 
The design and manufacture of HHW28 series products meet the requirements of GJB2438A-2002 “General specification for hybrid integrated circuit”, and the test method and procedure for electric circuit executes GJB548A-96 "Test methods and procedures for microelectronics".

4. Electrical performance (Table 2~5)Table 2  Rated conditions and recommended operating conditions 
Absolute max. rating Input voltage: 40V
Output power: 20W 
Lead soldering temperature: 300℃/(10s)
Storage temperature range: -55~125℃ 
Junction temperature: 175℃
Inhibit voltage: ≤0.2V
Recommended operating conditions Range of input DC voltage: 18~36V
Ambient temperature (TA): －55~＋85℃











Application notes: 
Upon power-on, be sure to correctly connect the positive and negative pole of the power supply to ensure correct power supply for fear of burnout. 
When carrying out the electrical performance test, the test position shall be the pinouts of the product. 
Upon assembly, the bottom of the product shall fit to the circuit board closely so as to avoid damage of pins, and shockproof provision shall be added, if necessary.
Do not bend the pinouts to prevent the insulator from breaking, which affects the sealing property.
When the case temperature is 105℃, it is suggested that the thickness of heat sinking plate (copper) shall be 3mm, and the area shall be greater than 80mm x 70mm. 
When the user places an order for the product, detailed electric performance indexes shall refer to the relevant enterprise standard.